1. Field of the Invention
The present invention relates to novel tannins and lipase inhibitors containing the same as effective ingredients.
2. Description of the Prior Art
Hitherto, an obesity has been shown to closely relate with diabetes, arteriosclerosis, hypertension and other adult diseases, and has become serious social problem in advanced nations. Obesity is usually caused by an excessive uptake of calories. Restriction of the intake of food would, however, likely cause excessive stress with practical difficulty in restriction.
Fat (triglyceride) is of the highest in calorie, among the food composition and an excess ingestion of fat directly causes obesity. Since fat is degraded by pancreatic lipase for absorption through the small intestine, several efforts have been devoted to develop medicines which inhibit an activity of pancreatic lipase to reduce or prevent obesity.
There are disclosed, for example, agents for anti-obesity and triglyceride reduction comprising polyethers in the Japanese Laid-open Patent Application No. 55-98114, and use of oxetanones in the Japanese Laid-open Patent Application No. 61-152663. Further, diethyl-p-nitrophenylphosphate and tetrahydrolipstatin working as lipase inhibitors have been reported by Biochem Biophys. Acta., 276, 162 (1972) and Biochem. J., 256, 357 (1988), respectively.
It is also reported that certain food components and crude drug components may inhibit lipase activity, for example, extracts of fruits or the like [Bull. Facul. Agric. Meiji Univ., 69, 15 (1985)], soybean proteins [Agric. Biol. Chem., 37, 1225 (1973)], cereal proteins [Nutrition reports International, 32, 1107 (1985)], and radish seed proteins [Journal of Japanese Food Industry Society, 35, 430 (1980)]. Further, hemicellulose [J. Food Sci., 49, 956 (1984)], wheat bran [Am. j. Clin. Nutr., 42, 629 (1985)] and phosphatidylcholine from radish seed [Bull. Facul. Agric. Meiji Univ., 73, 9 (1986)] have been reported to have inhibitory effects against lipase activity. Furthermore, the Japanese Laid-open Patent Application No. 1-102022 discloses lipase inhibitors consisting of specific components of oolong tea, the Japanese Laid-open Patent Application No. 3-219872 discloses lipase inhibitors consisting of water extracts from green peppers, pumpkins, champignons, Grifola frondosa, Hizikia fusiformis, green tea, red tea and/or oolong tea, and the Japanese Laid-open Patent Publication No. 3-228664 discloses food for inhibiting lipid absorption in combination with a principal component of green tea, epigallocatechin gallate.
As to tannins, meanwhile, it is known that those from feed plants inhibit lipase, amylase and protease activities [British J. Nutrition, 60,275 (1988)], and that extracts (tannins) from Fiel bean inhibit lipase activity [J. Sci. Food Agric., 30, 458 (1979)]. Further, galloyl quinic acid of the Japanese Patent Publication No. 60-50778, 3'-o-galloyldelphinidin B-2 of the Japanese Patent Publication No. 60-11912 and 4'-6'-galloylsalidroside of the Japanese Patent Publication No. 63-53993 have been published as novel tannins having effects of reducing activities of enzyme proteins in binding therewith, which are useful as metabolism controlling agents.
Furthermore, the Japanese Laid-open Patent Application No. 5-255100 discloses lipase inhibitors of extracts from crude drags, i.e., Angelicae pubscentis Radix, Galanga Rhizoma, Myricae Cortex, Nomame Herba and Cassia Semen, wherein Nomame Herba is a dried above-ground portion of Cassia nomame (=Cassia nomame Honda=Cassia mimosoides L. var. nomame Makino), and the inventors of the present application have uncovered that Cassia nomame contains two novel tannins (flavancatechin dimers) and then applied for patents of use as an agent for metabolism improvement under the Japanese Patent Application No. 5-210068 and of a flavonoid lipase inhibitor under the Japanese Patent Application No. 5-210067. These novel flavan-catechin dimers, however, could not achieve sufficient inhibitory effects against lipases.